The secret sauce of bass pros the world over, the Xtender gives you the ability to instantly drop the tuning of your low string and then back again with the flip of a lever. The BT7 is a direct replacement for Fender® Highway One tuning machines first featured on many MIM models. It is now a popular choice for many contemporary Fender® basses including Vintage Modified Squier®, USA, and Custom Shop models. Many smaller, independent builders have adopted this machine as well.